In recent years, a translucent resin, in particular, polycarbonate (PC) has been widely used as a lens for a vehicle lamp, due to its easy moldability into various shapes and lightweight.
In addition, although inorganic glass, mainly composed of silicic acid, is commonly used as a window member for a transportation unit including a vehicle, PC has been considered as a substitute for the inorganic glass and practically used in some fields for the same reason as in the lens for the vehicle lamp and due to its lighter weight and higher impact resistance, compared with the inorganic glass.
Meanwhile, PC has disadvantages of low weather resistance, such as secular degradation caused by ultraviolet (UV) light and a reduced transmittance due to yellowing, and low abrasion resistance, such as a surface susceptible to damage. Such disadvantages may be solved by forming a silicon-based hard coat layer on a PC substrate and additionally forming thereon a silicon dioxide (SiO2) layer by a plasma chemical vapor deposition (CVD).
However, the aforementioned silicon-based hard coat layer is formed by thermal curing. The silicon-based hard coat layer is subjected to the thermal curing for a relatively long period of time, for example, 30 minutes to 60 minutes. Therefore, using the silicon-based hard coat layer may lead to low productivity and high manufacturing costs.
Japanese Patent Laid-Open Publication No. 2011-126026 discloses a translucent resin member in which an acrylic hard coat layer is used in place of the silicon-based hard coat layer, that is, an acrylic hard coat layer and a SiO2 layer formed by plasma CVD are sequentially provided on a PC substrate. Since the curing of the acrylic hard coat layer is completed within a few minutes, using the acrylic hard coat layer may achieve enhanced productivity and reduced manufacturing costs.